fix: upgrade aiohttp pin to resolve ccxt dependency conflict

ccxt requires aiohttp>=3.10.11, was pinned to ==3.9.3.
python-binance has no upper bound on aiohttp, so this is safe.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

requirements.txt

@@ -5,7 +5,7 @@ python-dotenv==1.0.0
 httpx>=0.27.0
 pytest>=8.1.0
 pytest-asyncio>=0.24.0
-aiohttp==3.9.3
+aiohttp>=3.10.11
 websockets==12.0
 loguru==0.7.2
 lightgbm>=4.3.0